-- Discussion containing changed information from previous version are highlighted. --
677
FXUS61 KPBZ 170753
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
353 AM EDT Mon Jun 17 2024

.SYNOPSIS...
Heat will slowly build across the region this week. Hottest
temperatures are anticipated Wednesday through Friday. Isolated
showers and storms are possible this afternoon and again on
Tuesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:

- Heat begins to build in across the region.
- Weak shortwave activity may stir isolated showers/storms this
  afternoon

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A slow amplification of the eastern CONUS ridge is expected
today. This ridge will continue to spread warmer air across the
region. High temperatures today could be a bit tricky as a
shortwave trough moving over top of the ridge could bring an
increase in cu and the threat for showers and storms.
Development will be tough underneath the ridge and with the very
warm air aloft, but a popup shower or storm during peak heating
cannot be ruled out.

It will become more humid today as surface dewpoints will reach
the upper 60s to lower 70s this afternoon. Probabilities of
high temperatures > 95 today are focused on valleys and rural
areas. Outside of those locales, SE Ohio would have the best
chance of reaching 95 as probs are generally 25 to 35%.

With increasing dewpoints, heat indices will approach 100
degrees this afternoon across most of the forecast area.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
KEY MESSAGES:

- Heat continues to build through midweek.
- Isolated storms possible Tuesday afternoon.
- Dry and hot Wednesday.

-------------------------------------------------------------------

Ridge will continue to amplify on Tuesday, allowing surface heat
to slowly increase. As with Monday, high temperatures Tuesday
will depend heavily on the development of cu and possible
afternoon showers and storms. CAMs are showing convection firing
Tuesday afternoon, with focus on the higher elevations. This is
due to the low level flow on the backside of the Atlantic high.
A southeasterly surface wind will enhance orographic effects
which could be enough to overcome the subsidence from the very
strong ridge. If convection does fire Tuesday afternoon,
outflows from storms could run down the western side of the
ridges and develop more activity away from the mountains. This
threat should come into better focus over the next couple of
model runs.

Probabilities for high temperatures > 95 on Tuesday increase and
overspread more of the area. The most likely areas remain in the
valleys and rural areas, but probs of 40 to 50% are now spread
across a large portion of the region outside of the higher
elevations.

Ridge will be firmly in place by Wednesday with ensembles
showing heights of 597-599dm. 850 temperatures will remain very
warm and if much of the area stays dry Monday and Tuesday, we
could see even hotter temperatures on Wednesday. The threat for
convection should decrease on Wednesday with the region well
underneath the large ridge. CAM models are showing no activity
on Wednesday, which is in agreement with other operational
models as well.

Probs of > 95 degrees on Wednesday continue to increase with 40
to 60% covering most of the region outside of the mountains.

With hotter temperatures and high dewpoints, heat indices will
remain near or above 100 Tuesday and Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
KEY MESSAGES:

- High confidence in a dangerous heat wave holding through the
  end of the week with heat impacts possible.
- Probabilities are pointing to Thursday and Friday being the
  hottest days of the week.

-------------------------------------------------------------------

The highly anomalous ridge will remain in place Thursday, but
ensemble data is now hinting the ridge will begin to slowly weaken
on Friday.

Thursday and Friday should be dry as the area will remain under
the influence of the ridge`s subsidence.

Probabilities for high temperatures > 95 both Thursday and
Friday are the highest of the week. The higher probabilities
are also spread out more Thursday and Friday. Generally looking
at probs of 50 to 80% both days.

With surface dewpoints remaining in the upper 60s to lower 70s,
heat indices will continue to hold right around 100 degrees.

This would mean at least 5 days of daytime heat indices near 100
degrees.

Considering heat effect will be cumulative, late week is looking
particularly dangerous. The early season event, and
temperatures increasing slightly each day, will compound any
existing heat issues.

Potential impacts include heightened heat-related illnesses and
power grid issues with increased demand. It is strongly
encouraged to know where cooling shelters are located and stay
hydrated. There may be little relief at night. Make a list of
friends and family to check on and help them prepare.
Prolonged exposure to excessive heat was the primary cause of
weather-related fatalities in 2023.

This certainly is increasing slightly that there will be some
relaxation to the heat by early next week, but any relaxation
will still leave temperatures well above average. In the
Saturday-Sunday timeframe, all clusters reflect some flattening
of the ridge, but disagree on the degree of flattening. Some
maintain zonal flow or perhaps even weak eastern troughing early
next week, but even the coolest scenarios have temperatures
around average to start next week. The warmest scenarios
maintain near-record heat. SHould we stay quasi-zonal into next
week, we may get slight relief, but there as a notable fraction
on ensemble guidance that redevelops eastern ridging. CPC
maintains a moderate risk of excessive heat through 6/24.

Please see the Climate section below for more numerical details on
the kinds of records that may be in jeopardy.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Building high pressure will keep VFR conditions with light winds
in the forecast through the TAF period. The exception to this
may be isolated storms this afternoon as a weak shortwave
passes. However, strong subsidence with the building ridge is
likely to limit convective development, and with weak flow,
confidence is low on the location of any storms that do form.
Due to low probability and low confidence of
occurrence/location, have opted to not mention impacts in the
TAFs with this package.

.Outlook...
High probability for VFR and dry weather through the week as
strong ridging develops aloft.

The only variance may come with isolated afternoon convection
on Tuesday, but upper ridging should suppress coverage and
potential initiation.

&&

.CLIMATE...
The area has the potential to break various heat-related
records.

There is low probability that climate sites approach the
highest temperatures recorded in the 21st century:

Pittsburgh, PA:       98F  (7/7/2012)
Wheeling, WV:         98F  (7/7/2012)
Morgantown, WV:       101F (7/7/2012)
New Philadelphia, OH: 101F (7/7/2012)
Zanesville, OH:       101F (7/7/2012)
DuBois, PA:           101F (7/22/2011)

There is a modest probability many June all-time temperature
records may be at stake:

Pittsburgh, PA:       98F  (1988)
Wheeling, WV:         100F (1933)
Morgantown, WV:       99F  (1893)
New Philadelphia, OH: 99F  (1988)
Zanesville, OH:       101F (1988,1934)
DuBois, PA:           92F  (1969)

Daily high maximum (left) and high minimum (right) temperature
records are at stake for:

Monday, June 17th
Pittsburgh, PA:       95F  (1994)     75F  (1892)
Wheeling, WV:         99F  (1936)     69F  (2004)
Morgantown, WV:       95F  (1967)     72F  (1939)
New Philadelphia, OH: 95F  (1967)     69F  (2022)
Zanesville, OH:       99F  (1936)     72F  (1994)
DuBois, PA:           89F  (1994)     66F  (1892)

Tuesday, June 18th
Pittsburgh, PA:       97F  (1994)     73F  (1905)
Wheeling, WV:         95F  (1944)     71F  (2018)
Morgantown, WV:       95F  (1994)     70F  (2018)
New Philadelphia, OH: 95F  (1994)     72F  (2017)
Zanesville, OH:       99F  (1944)     73F  (1944)
DuBois, PA:           89F  (2018)     69F  (2018)

Wednesday, June 19th
Pittsburgh, PA:       97F  (1994)     74F  (1905)
Wheeling, WV:         95F  (1933)     70F  (2021)
Morgantown, WV:       94F  (1994)     72F  (2018)
New Philadelphia, OH: 92F  (1994)     70F  (2018)
Zanesville, OH:       94F  (1994)     75F  (1897)
DuBois, PA:           87F  (2001)     66F  (1975)

Thursday, June 20th
Pittsburgh, PA:       95F  (1994)     78F  (1924)
Wheeling, WV:         97F  (1933)     70F  (1924)
Morgantown, WV:       99F  (1893)     75F  (1924)
New Philadelphia, OH: 95F  (1994)     71F  (2009)
Zanesville, OH:       98F  (1934)     75F  (1924)
DuBois, PA:           89F  (1991)     66F  (1996)

Friday, June 21st
Pittsburgh, PA:       95F  (1933)     73F  (1934)
Wheeling, WV:         99F  (1933)     69F  (2016)
Morgantown, WV:       95F  (1953)     72F  (1988)
New Philadelphia, OH: 94F  (1994)     72F  (2016)
Zanesville, OH:       97F  (1988)     72F  (1997)
DuBois, PA:           89F  (1991)     68F  (1988)

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...Heat Advisory from 11 AM this morning to 8 PM EDT Friday for
     PAZ007>009-013>016-020>022-029-031-073>078.
OH...Heat Advisory from 11 AM this morning to 8 PM EDT Friday for
     OHZ039>041-048>050-057>059-068-069.
WV...Heat Advisory from 11 AM this morning to 8 PM EDT Friday for
     WVZ001>004-012-021-509>511.
-- End Changed Discussion --

&&

$$

SYNOPSIS...22
NEAR TERM...22
SHORT TERM...22
LONG TERM...22/CL/Milcarek
AVIATION...Rackley
CLIMATE...